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Relative size of combatants

"Hell's Gate" and "Hell Hath No Fury", by David, Linda Evans, and Joelle Presby, take the clash of science and magic to a whole new dimension...join us in a friendly discussion of this engrossing series!
Re: Relative size of combatants
Post by Jonathan_S   » Tue Jul 21, 2015 10:08 pm

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bkwormlisa wrote:Jonathan:

When it comes to a ropeway down the cliff into Karys, I fully agree that they couldn't simply put a rope at the top and connect it to a tower at the bottom. But I think what Mil-tech Bard is suggesting is having the ropeway towers perpendicular to the cliff, not the ground. That is, there would be supports sticking out from the cliff every few hundred feet, so the ropeway would angle down much as the Cut eventually would, hugging the cliff all the way. That would give the cables the frequent support they need and allow an angle much shallower than 45 degrees. I agree with him that that is possible, though it's not a type of ropeway we tend to build on Earth. We avoid slopes that steep because we can.

He finally did say that and I agreed that would work.

You'd have to run it laterally for over a km along the cliff face, but by doing that you can keep the rope angle, and distance between towers, down to something that will work without running into the elevator problem.


But I still don't see why the engineer's working on making the cut would need or want to do that. It's easier, and sufficient, to make the cut from the mountain slope on the Traisum side rather than from the cliff on the Karys side.
But I guess it's not impossible that they put in something to allow limited exploration past the future site of the cut while work on the cut progressed.


However, circling way back the the starting point of the discussion, even if such a ropeway existed I don't think you can use it for military attacks or raids into Karys. It's too exposed to Arcana fire until you drive them back from the portal. And once you drive them back you can use the much faster and higher payload cut rail or road; so you still don't need to use (or reinstall) any ropeway that might be left over from the construction period.
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Re: Relative size of combatants
Post by Mil-tech bard   » Wed Jul 22, 2015 11:58 am

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brnicholas

On the face of it, this looks like a "There are too many battle dragons" problem for RFC.

We shall see if that is so in the next few snippets...whenever they arrive.

brnicholas wrote:Yet my quotes from HHNF say explicitly that the sidings were put in to support the digging of the Traisum cut and Fort Salby's status as the end of the line. There are a number of ways to read these quotes together including Howard's suggesting that the rail head being referred to here bypasses a rail ferry the Sharonans had been using to move trains across the Red Sea. It seems far more probable to me Janaki is either in error (for Janaki's reliability note that the line was well past Fort Salby by the time Darcel arrived) or referring to something other then the first arrival of trains at Fort Salby. So there was a railroad available to bring supplies in for digging the Traisum cut.

Nicholas
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Re: Relative size of combatants
Post by Castenea   » Wed Jul 22, 2015 2:49 pm

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Jonathan_S wrote:

However, circling way back the the starting point of the discussion, even if such a ropeway existed I don't think you can use it for military attacks or raids into Karys. It's too exposed to Arcana fire until you drive them back from the portal. And once you drive them back you can use the much faster and higher payload cut rail or road; so you still don't need to use (or reinstall) any ropeway that might be left over from the construction period.

The ropeways that would be reinstalled would be up the mountain on either side of the cut and one perpendicular to those two, all to supply the Sharonian guns that prevent the Arcanans from controlling the cut or the ramp leading to the cut.
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Re: Relative size of combatants
Post by bkwormlisa   » Fri Jul 24, 2015 7:44 am

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Mil-tech bard wrote:Jonathan_S, bkwormlisa

Both of you seem to have a very...flawed...understanding of the tensile strength of steel cable and what that means in terms of ropeway vertical lift capability over distance.

Snip

Mil-tech bard:

Please stop insisting we have said things we have not, or claiming that we have ignored your evidence. Jonathan and I have both agreed that it is perfectly possible to put a ropeway from Traisum into Karys, as long as it goes along the cliff and has frequent supports. That is indeed within the capabilities of the 1911 ropeways, as you have very clearly demonstrated. Such a ropeway would have been a logical thing for them to put in while working on the Cut, in order to allow further exploration and perhaps move materials needed for finishing the Cut. Ropeways are cheap enough and quick enough to put up to make sense for that. I completely agree with you there.

What we are arguing is that there is no evidence we have ever, even with today's technology (much less the technology the Sharonians have), made a ropeway that is 6200 feet long and steep with absolutely no towers to support it over that distance.

And no, nothing you have presented so far gives that evidence, because none of it talks about unsupported spans. I have posted links to two much more modern ropeways that have longer spans without support (https://en.wikipedia.org/wiki/Feldmoos-Chli-Titlis_Aerial_Tramway and https://en.wikipedia.org/wiki/Peak_2_Peak_Gondola), but both were relatively modern, Peak 2 Peak was close to horizontal. And while Feldmoos-Chli-Titlis had an unsupported length of 11,368 ft and a total altitude difference of 4866 ft, I haven't been able to find out what the actual altitude change and/or angle of the unsupported section was. And again, it was built in 1979, with technology the Sharonians don't have.

And yes, even the quality and strength of steel cables has changed over time, and the ability to calculate safety margins more accurately has changed what we can (or are willing to) build. We don't currently have any information on the quality of Sharonian steel or how well they can calculate factors of safety, so we don't know where they fall there. We have to make assumptions, so I am assuming their construction abilities are no more advanced than ours at a similar technology level, no matter how much actual experience they have. Experience and rule of thumb building don't require the understanding it takes to make detailed calculations (the best of which require computers they don't have). You may be making different assumptions than I am, but they're still assumptions.

Until you come up with evidence that we were capable when we had Sharonian tech of building ropeways going straight off the cliff with the combination of length and steepness required for Traisum/Karys with no supports at all, I will not assume that the Sharonians can. No ropeway, however long or covering any altitude change, is evidence of that unless it very specifically mentions the capability required by the distance, angle, and lack of support that the Traisum/Karys ropeway would have under that specific circumstance. A single support would vastly change the strains on such a system.

And since a ropeway would have worked perfectly well along the cliff, the Sharonians had no need to do it the way I'm arguing they couldn't have, so why does it really matter that they couldn't do it a harder and less safe way? Engineering designs usually choose longer shallower paths over steeper and more dangerous ones for multiple reasons whenever possible, so they would have wanted to run it along the cliff anyway. They could still have made a ropeway there, and that's really all that matters.

Castenea wrote:
Jonathan_S wrote:However, circling way back the the starting point of the discussion, even if such a ropeway existed I don't think you can use it for military attacks or raids into Karys. It's too exposed to Arcana fire until you drive them back from the portal. And once you drive them back you can use the much faster and higher payload cut rail or road; so you still don't need to use (or reinstall) any ropeway that might be left over from the construction period.

The ropeways that would be reinstalled would be up the mountain on either side of the cut and one perpendicular to those two, all to supply the Sharonian guns that prevent the Arcanans from controlling the cut or the ramp leading to the cut.

I don't understand this proposal. What do you mean, "The ropeways that would be reinstalled would be up the mountain on either side of the cut and one perpendicular to those two"?
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Re: Relative size of combatants
Post by Jonathan_S   » Fri Jul 24, 2015 12:10 pm

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bkwormlisa wrote:
Castenea wrote:The ropeways that would be reinstalled would be up the mountain on either side of the cut and one perpendicular to those two, all to supply the Sharonian guns that prevent the Arcanans from controlling the cut or the ramp leading to the cut.

I don't understand this proposal. What do you mean, "The ropeways that would be reinstalled would be up the mountain on either side of the cut and one perpendicular to those two"?

I think Castenea is arguing for ropeways only on the Traisum side of the portal; presumably to support troops, AA guns, and artillery up near the ridge line.

I'll say again that this seems reasonable to me; the Arcanans can't attack it at long range because they'd have to penetrate the portal before their weapons can engage, while the Sharonan guns can take them under fire through the portal.

One ropeway across the cut to let people and supplies be shuttled horizontally along behind the ridge line; then a couple supply ropeway parallel to the cut to feed supplies and men up the mountain to gun emplacements.


Three ropeways might be a little overkill, though there's something to be said for the redundancy that provides. Unlike the ropeway down the cliff into Karys there's no real technical difficulty to installing on the Traisum mountain slopes; and it's not anywhere near as vulnerable to Arcanan attack as one penetrating the portal would be.
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Re: Relative size of combatants
Post by Louis R   » Fri Jul 24, 2015 1:51 pm

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Unless you're a licensed civil engineer, and are willing to share your analysis with us, I'm going to have to call BS on this one. A finished design isn't required, but there should be enough detail to show how likely rock types and geologic and meteorologic conditions and the operating conditions of the system are being taken into account.

No, I'm not a civil engineer, nor have I played one on TV, but working as a medical engineer I had just enough experience anchoring heavy equipment in friable matrices to be very sure that anybody calling this feat 'trivial' had damned well better be wearing an iron ring. I'm not at all sure that we could build this now, never mind the Sharonans, but if we could it would depend on capabilities that have only become available in the last 30 years. Detailed finite-element analysis of the support cantilever, required to design the anchor system. High-stress deep-rock anchors. The ability to extrapolate bulk properties of rock from small bore-hole samples [and you wouldn't catch me taking those samples, either!]. And on, and on, and on.

Building out of rock is a very different challenge from building _on_ rock, and the biggest part of that is the fact that stone has essentially zero tensile strength. And unsupported cantilevers without counter-weights will be pulling on the rock in spades. Any mistakes in the distribution of the tension and the system peels off the cliff. In sedimentary or low-grade metamorphic sections of the cliff it's very likely the profiling and calculations will have to be performed separately for each anchor point - in fact, it wouldn't surprise me if every support arm was a unique design. The standard 19th-century engineering practice of overbuilding everything won't work in this case because it just makes it more likely that you'll over-stress the rock itself.


bkwormlisa wrote:< snip >
And since a ropeway would have worked perfectly well along the cliff, the Sharonians had no need to do it the way I'm arguing they couldn't have, so why does it really matter that they couldn't do it a harder and less safe way? Engineering designs usually choose longer shallower paths over steeper and more dangerous ones for multiple reasons whenever possible, so they would have wanted to run it along the cliff anyway. They could still have made a ropeway there, and that's really all that matters.

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Re: Relative size of combatants
Post by PeterZ   » Fri Jul 24, 2015 3:42 pm

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One suspects Plotters(?) like Jathmar can provide the material analysis of the rocks without drilling for samples. One trained in engineering can design/map out the support structure necessary to hold the designed rope way.
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Re: Relative size of combatants
Post by Castenea   » Fri Jul 24, 2015 3:54 pm

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Jonathan_S wrote:I think Castenea is arguing for ropeways only on the Traisum side of the portal; presumably to support troops, AA guns, and artillery up near the ridge line.

I'll say again that this seems reasonable to me; the Arcanans can't attack it at long range because they'd have to penetrate the portal before their weapons can engage, while the Sharonan guns can take them under fire through the portal.

One ropeway across the cut to let people and supplies be shuttled horizontally along behind the ridge line; then a couple supply ropeway parallel to the cut to feed supplies and men up the mountain to gun emplacements.


Three ropeways might be a little overkill, though there's something to be said for the redundancy that provides. Unlike the ropeway down the cliff into Karys there's no real technical difficulty to installing on the Traisum mountain slopes; and it's not anywhere near as vulnerable to Arcanan attack as one penetrating the portal would be.

Thank you for explaining my proposal for the use of ropeways in the immediate future of the multiverse much better than I seem to have.

Louis, I will question your conclusion that anchors could not be placed on the vertical cliff, I will agree that any safety organization today would freak at the methods required to install those anchors with ~1900 tech. Wielding a rock drill while in a bosuns chair in full sun? Not fun.
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Re: Relative size of combatants
Post by bkwormlisa   » Fri Jul 24, 2015 5:19 pm

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My engineering degrees are mechanical and aerospace, not civil, and I haven't done any analyses. My estimates are in my head only. No, building a ropeway there would be far from trivial. It would, in fact, be a very difficult and dangerous thing to do. Nonetheless, they must have done something to get supplies down the cliff before the Cut was finished (textev is that they continued exploring while the Cut was being made), and I think a ropeway along the cliff is far more possible than a single line anchored only at the top or bottom. Or than elevators of some kind.

Given that they have Mappers, they can find the best rock with far more ease and precision than we could, and that is very important for this. If I remember correctly, these mountains are the Rockies, and so are mostly igneous rock, rather than sedimentary. And the cliff has some significant erosion, so it isn't actually flat vertical with no features.

The system as I envision it either has the "towers" on niches that are close to level (probably blasted out at the flattest spots) or is cantilevered. If cantilevered, it would have broad plates to spread the weight of the cantilever, bolts driven at an angle to put as much of the force as possible with gravity, and be anchored at only the strongest spots, even though the towers would be unevenly spaced. In either case, it would be capable of only limited weights. It would be a temporary measure, used only until the Cut was finished.
Louis R wrote:Unless you're a licensed civil engineer, and are willing to share your analysis with us, I'm going to have to call BS on this one. A finished design isn't required, but there should be enough detail to show how likely rock types and geologic and meteorologic conditions and the operating conditions of the system are being taken into account.

No, I'm not a civil engineer, nor have I played one on TV, but working as a medical engineer I had just enough experience anchoring heavy equipment in friable matrices to be very sure that anybody calling this feat 'trivial' had damned well better be wearing an iron ring. I'm not at all sure that we could build this now, never mind the Sharonans, but if we could it would depend on capabilities that have only become available in the last 30 years. Detailed finite-element analysis of the support cantilever, required to design the anchor system. High-stress deep-rock anchors. The ability to extrapolate bulk properties of rock from small bore-hole samples [and you wouldn't catch me taking those samples, either!]. And on, and on, and on.

Building out of rock is a very different challenge from building _on_ rock, and the biggest part of that is the fact that stone has essentially zero tensile strength. And unsupported cantilevers without counter-weights will be pulling on the rock in spades. Any mistakes in the distribution of the tension and the system peels off the cliff. In sedimentary or low-grade metamorphic sections of the cliff it's very likely the profiling and calculations will have to be performed separately for each anchor point - in fact, it wouldn't surprise me if every support arm was a unique design. The standard 19th-century engineering practice of overbuilding everything won't work in this case because it just makes it more likely that you'll over-stress the rock itself.
bkwormlisa wrote:< snip >
And since a ropeway would have worked perfectly well along the cliff, the Sharonians had no need to do it the way I'm arguing they couldn't have, so why does it really matter that they couldn't do it a harder and less safe way? Engineering designs usually choose longer shallower paths over steeper and more dangerous ones for multiple reasons whenever possible, so they would have wanted to run it along the cliff anyway. They could still have made a ropeway there, and that's really all that matters.
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Re: Relative size of combatants
Post by brnicholas   » Sat Jul 25, 2015 9:36 am

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This is a nitpick but what textev are you thinking of here?

I don't recall the text ever saying when the cut was finished. It isn't inconceivable to me that they finished the cut five years ago and hadn't extended the railroad past Salbytown at the beginning of Hell's Gate because exploration only started after the cut was finished and there wasn't enough development beyond the cut yet to justify extending the railroad.

Nicholas

bkwormlisa wrote:...snipped...

(textev is that they continued exploring while the Cut was being made)

...snipped...
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